Non union of the fracture is the condition of cessation of all reparative processes of healing of fracture without bone union [1-3]. Non union can also be described as the absence of progressive repair that has not been observed radiographically between the 3rd and the 6th month following the fracture [2, 4]. Non-union may occur either as a result of poor mechanical or biological environment on the fracture area or as a combination of the two [2]. This and other situations require manipulation or augmentation of natural healing mechanisms to regenerate large quantities of new bone than would naturally occur to achieve surgical goals [5-7]. Therefore, new bone for the repair or the restoration of the function of traumatized, damaged, or lost bone is a major clinical need, and bone tissue engineering has been heralded as an alternative strategy for regenerating bone [8].
Tissue engineering, as it applies to bone, focuses on restoration of large segments of skeleton including weight bearing bones. Bone can be regenerated through the following strategies: Osteogenesis—the transfer of cells; Osteoinduction—the induction of cells to become bone; Osteoconduction—providing a scaffold for bone forming cells; or Osteopromotion—the promotion of bone healing and regeneration by encouraging the biologic or mechanical environment of the healing or regenerating tissues.
A polymeric poly (L-lactide) tubular membrane spanning a mechanically stable, large segmental bone defect was shown to promote woven bone formation and reconstruction of the bone defect [9]. Mosheiff et al. developed a critical size defect model in rabbit for bone loss treatment testing. In this model the rabbit forearm is to produce critical size defect. A critical size defect is defined as the smallest intraosseus wound that is not bridged by the skeleton in normal circumstances [10, 11]. Using this model, our group has successfully employed membranes for guided bone regeneration (GBR), by osteoconduction [10, 12].
Gugala et al. demonstrated homogenous growth of mesenchymal stem cells (MSC) on porous membranes, forming a three-dimensional fibrillar network [19].
WO 2005/107826 discloses moldable bone implants comprising biocompatible granules (e.g. bioceramics), a biocompatible polymer and a plasticizer. The implant may form an open porous scaffolding or composite matrix or may be administered as a liquid or plastically deformable implant.
WO 2004/084968 discloses a porous matrix suitable for use as a tissue scaffold or an injectable formulation, preferably prepared from a degradable cross-linked polymer.